This invention relates to applicators for line marking on surfaces such as roads, car parks, factory floors and playing areas including gymnasium floors, basket ball courts, artificially-turfed and naturally-turfed playing fields and the like. Our European Patent Specification No. 0 678 624 A2 discloses a line marking applicator comprising a frame having an axle on which is journalled a pair of surface contacting wheels and a mounting for a marker fluid aerosol dispenser positioned on the frame so that, when fitted with an aerosol dispenser and in use, marker fluid can be sprayed between the wheels onto a surface, the width of the sprayed line being defined by the spacing between the wheels, each of the wheels having an integral inner surface extending contiguously from the axle to a rim having a smaller diameter than that of the wheel rim and which is axially inwardly offset from the wheel rim to provide a circumferential groove, preferably each wheel is provided with a tire, the diameter of which is greater than the diameter of the inner surface rim and which is axially offset from the inner surface rim to form the peripheral groove.